Abstract: At present, all the SEC reserves evaluation of coalbed methane fields uses dynamic assessment methods. In the process of evaluation, the parameters and calculation results are various. In order to solve this problem, this paper takes the Hancheng block in Ordos basin as an example, a series of evaluation methods adapted to the production characteristics of coalbed methane have been comprehensively applied, optimizing various parameters, and summarizing the law of decline. The results show that geological units are divided according to tectonic conditions, and on this basis, evaluation units are divided according to development effect, which can objectively and reasonably analyze the law of coalbed methane field decline. A typical curve of dynamic reserves reduction, such as exponential decline, hyperbolic decline and harmonic decline, can be used to test the reasonableness of the results of reserves evaluation. For an evaluation unit, in the process of reserve evaluation, the effect of late production increase measures should be taken into full consideration when the value of decline rate is taken into account.